TL;DR: In this article, a trilobite faunas of Ordovician and Silurian age can be recognized based on graptolites, and two new genera and species are described: Murphycops skidmorei (Phacopinae) and Portaginus robustus (Illaenacea).
Abstract: Distinctive trilobite faunas of Ordovician and Silurian age can be recognized. An Upper Caradoc fauna is based on graptolites. Two Lower or Middle Ashgill trilobite faunas can be separated: a lower Stenopareia and an upper Remipyga fauna. An Upper Ashgill, or Dalmanitina fauna, is reported for the first time in the New World. Silurian fossils, recognized for the first time in the White Head, can be divided into a Lower Llandovery and an undifferentiated (no younger than middle Upper) Llandovery fauna. Classification of the Phacopidae is reviewed; Phacopidella is removed from the family, and Eophacops is considered a junior synonym of Denckmannites. Two new genera and species are described: Murphycops skidmorei (Phacopinae), and Portaginus robustus (Illaenacea) as the type of a new family, Portaginidae.
TL;DR: Early Silurian trilobites and graptolites from the Vargas Pena Formation of the western Parana Basin are described in this paper, and the taxa recognized suggest a?late Rhuddanian to late Aeronian/early Telychian age.
Abstract: Early Silurian trilobites and graptolites from the Vargas Pena Formation of the western Parana Basin are described. The studied material comes from two successions (San Fernando and Galeano quarries) on the southwestern flank of the Ypacarai graben, about 30 km southeast of Asuncion city, eastern Paraguay. The faunas include Calymene boettneri Harrington, C. harringtoni tortello sp. nov., Trimerus sp., Dalmanites ypacarayensis (BalDis & Hansen), Dalmanites sp., Guaranites paraguayensis BalDis & Hansen, Eophacops sp., Normalograptus cf. ajjeri (legranD), N. aff. rectangularis (mccoy), Metaclimacograptus cf. asejradi legranD, Paraclimacograptus innotatus (nicHolson), and P. brasiliensis (rueDemann). The taxa recognized suggest a ?late Rhuddanian to late Aeronian/early Telychian age for the Vargas Pena Formation. The graptolites constitute a low diversity, oxygen tolerant fauna that would be indicative of shallow water conditions, an environment that is also supported by the occurrence of the trilobite genus Trimerus.